3.4 Cacheing and Dispatch Functions

SB-PCL::CACHING functions simply cache effective methods as a
function of argument wrappers, while SB-PCL::DISPATCH functions
have code that computes the actual dispatch. SB-PCL::CHECKING
functions have a cache, but on cache misses will recompute whether or
not to generate a SB-PCL::CACHING or SB-PCL::DISPATCH
function.

(FIXME: I'm actually not certain about the above paragraph. Read the
code again and see if it makes any more sense.)